AXPZ20 KNHC 311520

1605 UTC TUE MAY 31 2016

Tropical weather discussion for the eastern Pacific Ocean from the Equator to 32N, east of 140W. The following information is based on satellite imagery, weather observations, radar, and meteorological analysis.

Based on 1200 UTC surface analysis and satellite imagery through 1500 UTC.


Tropical wave is along 12N92W 09N94W 05N95W. Convective precipitation: scattered to numerous strong from 05N to 08N between 93W and 97W. Scattered moderate to isolated strong from 04N to 08N between 91W and 93W.


The monsoon trough extends from 12N86W to 12N93W to low pres near 09N110W to low pres near 10N115W to 07N121W. ITCZ extends from 07N121W to beyond 07N140W. Scattered moderate isolated strong convection from 06N to 11N between 92W and 108W.


A cold front about 180 nm west of 140W extends from a 1012 mb low near 32N143W to 26N143W. The front is being blocked by a N-S oriented surface ridge along 133W extending south from 1022 mb high near 38N133W. The front will become stationary during the next 12-24 hours, and model guidance shows the front undergoing a complex transition to a trough then into a surface low north of 24N west of 140W through Wed. A broad subtropical ridge is expected to prevail over northern waters west of 113W through Thu. An elongated low pressure trough is analyzed along 9N-10N between 95W and 120W, with a pair of weak low centers identified near 09N110W and 10N115W. Satellite imagery shows broad cyclonic turning all along the trough axis but no clearly organized lows. Model consensus indicates a tropical low will develop out of the broad trough in 2-3 days, when environmental conditions will be more favorable for it to intensify into a tropical depression after breaking free of the convergence zone. In the interim, expect monsoonal W-SW flow south of the trough axis to gradually strengthen, which will allow seas to build to 8-9 ft in a broad area straddling 10N between 95W-120W through Thu afternoon.

$$ Mundell